Referring to FIG. 1, a conventional tool storage device 1 of Taiwanese Utility Model Patent No. M261345 includes a box body 11 and a replaceable retaining seat 12. The box body 11 includes a center plate portion 111 and two side cover portions 112 extending in opposite directions away from the center plate portion 111. Each of the side cover portions 112 has a folding section 113 to facilitate the folding of the two side portions 112 towards and engagingly with each other. However, the socket seat 12 of the conventional tool storage device 1 can only be coupled, albeit removably, to the center plate portion 111 and cannot be coupled to the side cover portions 112, resulting in inefficient space utilization within the conventional tool storage device 1. In addition, since the box body 11 has large weight and mass, the conventional tool storage device 1 also leaves much to be desired in terms of portability.
Referring to FIG. 2, a conventional tool storage device 2 of Taiwanese Utility Model Patent No. 275831 includes a main body 21, a trapezoid intermediary part 22 disposed within the main body 21, and a cover 23 to be sleeved over and around the main body 21. The main body 21 has a center plate portion 211 that allows the intermediary part 22 to be fixed thereon, and two extending portions 212 that extend toward each other respectively from two lateral sides of the center plate portion 211. The extending portions 212 adhere against each other and against the intermediary part 22, and are each formed with a plurality of clamp cavities 213 that allow placement of tool bits or sockets therein.
However, since the cross-section of the main body 21 is roughly in the shape of an isosceles triangle, the center of gravity lies closer to the top so that the conventional tool storage device 2 topples over easily. Furthermore, since each of the extending portions 212 is formed with a plurality of the clamp cavities 213, the structural strength of the main body 21 is in fact low, requiring the intermediary part 22 for support. Moreover, to prevent the tools in the clamp cavities 213 from falling out, the cover 23 is further required for blocking. The need for the intermediary part 22 and the cover 23 inevitably results in a heavier overall weight of the conventional tool storage device 2.